#!/usr/bin/env python
from math import *
import numpy as np
import pylab as pl
import scipy as sp
import sys as sys
#try:
 #   K  = float(sys.argv[1])
#except:
 #   print "Bitte Kopplungsstaerke angeben."
  #  sys.exit(1)

K=0.125
# die system parameter
la  = 0.25
w   = pi
tau = pi/w

# die numerik parameter
tfinal = 100

dt = 0.01
N = int(tfinal/dt)+1;
delta = int(tau/dt)


# initialisiere die Arrays
outx = np.zeros(N)
outy = np.zeros(N)

histx = np.zeros(delta)
histy = np.zeros(delta)

# die Anfangsbedingung
histx[0] = 1.0


x=1
y=1
for i in range(N):

    xtau = histx[(i)%delta]
    ytau = histy[(i)%delta]

    x = x + dt * ( la*x +  w*y - K*x + K*xtau )
    y = y + dt * ( -w*x + la*y - K*y + K*ytau )

    outx[i] = x
    outy[i] = y
    histx[(i)%delta] = x
    histy[(i)%delta] = y

pl.plot(1,1,'ro') 
pl.plot(outx, outy)
pl.show()